The disclosure relates to an electromagnetic impact valve arrangement for a pneumatically operated field device, in particular a positioning device of a processing plant, such as a chemical plant, for example a petrochemical plant, a food-processing plant, such as a brewery, a power plant, such as a nuclear power plant, or the like.
A generic electromagnetic impact valve arrangement comprising an impact plate as impact valve member is known from DE 196 36 207 C2, which has proved its worth in the past. The electromagnetic impact valve arrangement has a housing structure, in which typically an air supply conduit is formed for connecting an air pressure source, an air discharge conduit and a venting conduit. An impact member in the form of a baffle plate is movably supported inside the impact valve arrangement. An electromagnetic controller displaces the impact valve member between two operating positions, in which one of the air ducts is closed in each case. The impact valve member is displaced in an axial positioning direction. The magnetic valve furthermore has a biasing member, such as a spring, which urges the impact valve member in axial positioning direction into a closed position for closing one of the air conduit. The simple technical setup and the accurate position using the electro-pneumatic controller has thereby proved its worth. The known magnetic valve requires an accurate fabrication, in particular when an accurate closing of the respective air duct in the case of a low energy requirement is to be ensured.
Another generic electromagnetic impact valve arrangement is described in the German patent application with the official file number DE 10 2016 106 410.6. This electromagnetic impact valve arrangement comprises an impact valve comprising a movably supported impact valve ball. An electromagnetic controller displaces the impact valve member in an axial control direction between operating positions, in which either the air supply conduit or the venting conduit is closed. The impact ball cooperates with a disc-like, magnetizable impact baffle, which moves together with the impact ball. A biasing member, such as a spring, pushes the baffle plate with the impact valve ball against the opening edge of the supply conduit, to close the latter in an air-tight manner. In the case of the impact valve arrangement described in DE 10 2016 106 410.6, the adjusting axis runs coaxially to the axis of the electromagnet, the core of which is realized as hollow cylinder, in order to realize the ventilation duct. With persistently high reliability, the electromagnetic impact valve arrangement according to DE 10 2016 106 410.6 allows for the operation of a position controller with a significantly reduced energy requirement as compared to the impact value arrangement known from DE 196 362 07 C2.
If a certain control pressure for generating a certain positioning force is to be generated in one of the conventional impact valve arrangements, or if a certain volume flow is to be generated for adjusting the positioning speed of an actuator, the electromagnetic impact valve arrangement needs to continuously change back and forth between pressure increase and pressure reduction. The impact plate needs to assume a certain intermediate position. Alternatively for achieving a certain volume flow in the case of a conventional valve, in which intermediate state the venting conduit as well as the aeration conduit are open at the same time to keep a desired adjusting pressure or volume flow approximately constant. In the case of such an intermediate position or a continuous change, pneumatic compressed air is lost continuously.
The exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings.